Desorption Yields and Irradiation-Condition Dependence of Layer-by-Layer Removal for KBr(001) Surface Stimulated by Electrons

抄録

Desorption yields obtained from a KBr(001) surface irradiated by 1.5–3-keV electrons have been measured via layer-by-layer mode removal. The yields are obtained from the inverse electron fluences required to remove the monolayer, which are measured from the specular intensity oscillations of 15-keV protons incident on the surface with small angles (≤1°). The desorption yield dependence on electron energy and beam current density (range : ≤100 nA cm⁻²) of the incident electrons has been measured while varying the sample temperature (350–470 K). The electron energy dependence is weak, and there is no apparent beam current density dependence. However, the initial half-period of the intensity oscillation curve tends to extend, and the oscillation shifts to higher electron fluence with increasing electron energy, electron beam current density, and decreasing sample temperature. A possible explanation for the aggregation is provided via attributing this result to the existence of aggregated F centers.